• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.136-141
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• 1993

8 Wall specimens (1/2 scaled) used welded wire fabric (Ф=6mm) and ordinary deformed reinforcement(D6) of which their ultimate tensile strength were almost same were tested to investigate the inplane-flexural behavior. Test results show that : 1. The wall strength with welded wire fabric was 20% less than that with deformed bar. 2. The wall ductility ratio of welded wire fabric was 1/3 times than that of deformed bar, approximately. 3. It is recommened that lap splice of welded sire fabric should be avoided in critical fracture zone.

• International Journal of Concrete Structures and Materials
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• v.7 no.1
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• pp.61-69
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• 2013

This paper discusses the properties of RCA, the effects of RCA use on concrete material properties, and the large scale impact of RCA on structural members. The review study yielded the following findings in regards to concrete material properties: (1) replacing NA in concrete with RCA decreases the compressive strength, but yields comparable splitting tensile strength; (2) the modulus of rupture for RCA concrete was slightly less than that of conventional concrete, likely due to the weakened the interfacial transition zone from residual mortar; and (3) the modulus of elasticity is also lower than expected, caused by the more ductile aggregate. As far as the structural performance is concerned, beams with RCA did experience greater midspan deflections under a service load and smaller cracking moments. However, structural beams did not seem to be as affected by RCA content as materials tests. Most of all, the ultimate moment was moderately affected by RCA content. All in all, it is confirmed that the use of RCA is likely a viable option for structural use.

• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.1
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• pp.63-72
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• 1988

The primary objective of the study was to find the deformation characteristics of reinforced polymer concrete beams. A test program was carried out to compare the behavior in deformation of polyester and MMA concrete beams with cement concrete beams but with varying ratios of tensile reinforcement. From the results the following conclusions can be made. 1.The various strengths of polymer concrete ware very high compared to the strengths for cement concrete. Also, compared to conventional concrete beams, flexural strength of reinforced polymer concrete beams was distinctly higher for the same section and steel ratios. 2.The polymer concrete beams exhibit large deflections accompanied by relatively high strengths as compared to cement concrete beams. 3.The average ultimate strain at the extreme compression fiber of polymer concrete beams was 0.01 1 cm / cm, and this value was about three to four times as large as that of cement concrete beams, 4.The polymer concrete beams developed more cracks which were more wide crack distribution spacing than the cement concrete beams, and the beams failed in a more ductile manner. 5.The reinforcing steel ratio has a significant effect on the beam strength, load-deflection response, stress-strain curve, and crack pattern of polymer concrete beams.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.61-64
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• 2005

Concrete is one of the principal materials for the structure and it is widely used all over the world, but it shows extremely brittle failure under bending and tensile load. Recently to improve such a poor property, Ductile Fiber Reinforced Cementitious Composites (DFRCC) have been developed, and it are defined by an ultimate strength higher than their first cracking strength and the formation of multiple cracking during the inelastic deformation process. This paper is to estimate experimentally the mechanical properties of ductile concrete with the kinds of used fine and coarse aggregate for purpose of development of high ductile concrete mixing coarse aggregate. As the results, ductile concrete mixed coarse aggregate showed the displacement-hardening behavior under bending load similar to DFRCC, and its compressive and bending performance varied according to the kinds of used coarse aggregate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.1
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• pp.121-128
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• 1999

In this study, the behavior of R/C beams strengthened with carbon fiber laminate (CFL) is analyzed from the test results. CFL is attractive for this application due to its good tensile strength and low weight. Test parameters are the width and the thickness of CFL and repair of damaged specimen. The failure mode and ultimate load are analyzed from these measured data. Test results show that the peak load of specimens strengthened with CFL is increased to 1.27~2.04 times that of non-rehabilitation specimen. The wider lap width, larger amount of CFL, the larger strength is obtained. But the ductile behavior of the rehabilitated specimens is inversely proportional to the CFL thickness.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.280-281
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• 2006

Powder grades pre-alloyed with 1.5-3 wt% chromium can be successfully sintered at the conventional temperature $1120^{\circ}C$ although well-monitored sintering atmospheres are required to avoid oxidation. Mechanical properties of the Cr-alloyed PM grades are enhanced by a higher sintering temperature in the range $1120-1250^{\circ}C$, due to positive effects from pore rounding, increased density and more effective oxide reduction. Astaloy CrM (Fe-3 wt% Cr-0.5 wt% Mo) with 0.6 wt% graphite added obtains an ultimate tensile strength of 1470 MPa and an impact strength of 31 J at density $7.1\;g/cm^3$, after sintering at $1250^{\circ}C$ followed by cooling at $2.5^{\circ}C/s$ and tempering.

• Macromolecular Research
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• v.10 no.6
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• pp.369-372
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• 2002

The use of ZnO and stearic acid is very well known in sulfenamide accelerated sulfur vulcanization of diene elastomers. Zn-ion coated nano filler has been developed and tested, in styrene-butadiene rubber (SBR) as sulfur vulcanizing activator cum reinforcing filler. In this study Zinc oxide has been replaced by the Zn-ion coated nano silica filler with an aim to study the dual role of this nanofiller in SBR. The presence of Zn-ion on the nano silica filler surface activates the sulfur vulcanization by involving Zn++ in to the sulfurating complex formed with thiazole from sulfenamide. The increase of Zn-ion, on the nanofiller, decrease the scorch safety of the elastomer compound but increase the tensile strength, state of cure and tear strength and attain maximum at its 10% level. The presence of stearic acid increases the rate of vulcanization. Replacement of stearic acid with mono-stearate, however, increases the vulcanization rate but decrease the ultimate state of cure. A mechanistic scheme involving dual function of this nanofiller has been suggested.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.127-131
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• 2010

Carbon-epoxy prepreg has been introduced in the forming of the upper and lower swash plates that control the pitch of rotor blade of unmanned helicopter because of its lightweight. Taguchi experimental method has been used by introducing the variables such as arrangement angle, laminated number and forming temperature, in order to obtain the proper forming method by using prepreg satisfying the required strength of the swash plate. In the evaluation of structural safety for the swash plates, three kinds of models are considered by using FE-analysis. In comparison of the hot forged products with Al6061-T6 and the formed products with prepreg, it was found that ultimate tensile strength of the products with prepreg is three times higher than that of the Al6061-T6, and the weight reduction of 68.5g can be achieved by using prepreg swash plates.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.945-952
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• 2023

In this study, the sand casting process was applied to design the gating system and perform casting simulation in order to domestically produce the submarine mast cover. Based on simulation results, casting experiments were conducted to produce a soundness prototype. The design concept of the mast cover's gating system was based on the design of bell casting. By arranging eight tower-type gates in a circle at 45° intervals, the flow of melt flowing into each gate was uniform and did not mix with each other, and the velocity of melt was also uniform. The mast cover made of Ni-Al-Bronze alloy has no unfilled parts. However, small porosities and flow marks occurred on the surface in several places. Yield strength and ultimate tensile strength are 279.3 MPa and 675.7 MPa, respectively, and elongation is 21.2%.

• Journal of the Korean Society of Safety
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• v.24 no.2
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• pp.23-29
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• 2009

The hybrid composite materials are recently used in many field as an advanced material due to their high resistance to fracture. However, hybrid composite materials have several problems, especially delamination, compared with homogeneous materials such as an aluminum alloy, etc. In this study, we carried out the tensile test to study the tension failure appearances and tensile ultimate strength of CFRP/Al/CFRP hybrid composite materials. The CFRP material used in the experiment is a commercial material known as CU175NS in unidirectional carbon prepreg. Also Al/CFRP/Al hybrid composites with three kind length of a single edge crack were investigated for the relationship between an aluminium volume fraction and a crack length. The crack length was measured by a traveling microscope under a universal dynamic tester. Futhermore the stress intensity factor behavior was examined according to a volume fraction and an initial crack length ratio to a width.